The World Health Organization says that every year more than 3.4 million people die as a result of water related diseases, making it the leading cause of disease and death around the world. Most of the victims are young children, the vast majority of whom die of illnesses caused by organisms that thrive in water sources contaminated by raw sewage. VOA's Jessica Berman has more on the story.

A report published recently in the medical journal The Lancet concluded that poor water sanitation and a lack of safe drinking water take a greater human toll than war, terrorism and weapons of mass destruction combined.

According to an assessment commissioned by the United Nations, 4,000 children die each day as a result of diseases caused by ingestion of filthy water. The report says four out of every 10 people in the world, particularly those in Africa and Asia, do not have clean water to drink.

Resources analyst Erik Peterson, of the Center for Strategic and International Studies in Washington, describes the water crisis this way:

"At any given time, close to half the population of the developing world is suffering from waterborne diseases associated with inadequate provision of water and sanitation services," Mr. Peterson explained. "There are about four billion cases of diarrhea disease per year, resulting in about one or two million deaths, some ninety percent of which, tragically, are in children under the age of five."

Cholera, typhoid fever and hepatitis A are caused by bacteria, and are among the most common diarrheal diseases. Other illnesses, such as dysentery, are caused by parasites that live in water contaminated by the feces of sick individuals. Lakes and streams which people use for drinking water, bathing and defecating are sources of disease, as is water left by natural disasters. Last year's tsunami left victims in ankle-deep water, amid destroyed sewage pipes.

People can also contract a diarrheal disease by eating food that's prepared by sick individuals who have not washed their hands, or touching something handled by an infected person and then putting their own hands into their mouths.

Marla Smith-Nelson helped form Water Partners International, after becoming alarmed by the health impact of unclean water in some of the world's poorest countries.

"In Ethiopia, I believe one in five children are dying before they reach the age of five. So, we are working in countries that have significant water issues," she said. "But there are so many countries that have severe water issues, I don't want to paint a picture that we are working in the absolute worst places. I think it's probably a tie among a lot of different countries where there are issues."

Experts say there are both short term and long term measures that can be taken to prevent the spread of waterborne illnesses. In the short term, they say people should wash their hands as much as possible, use a latrine, even if it's a hole in the ground, and boil water and store it.

For the long term, communities must have sources of clean drinking water. Ms. Smith-Nelson says up to 50 percent of places with unsafe drinking water once had systems that functioned, but they fell apart due to lack of maintenance. Her group helps rebuild water systems and shows local people how to set up local governing bodies to run them.

The organization has worked in communities in nations as diverse as Bangladesh and Honduras.

"One of the biggest systems that we funded involved 50 miles of pipeline trench that was dug entirely by hand by the community itself," she explained, " which I think was a great example to me, and I think a great example to anybody who works with us, on the significance of these water systems, of how badly they're wanted by the community, the fact that local people would put in two years of hard labor to dig a trench to get water to their community."

Analysts say eliminating disease and death due to unclean water and poor sanitation would reap billions of dollars in health and productivity gains. They estimate that for every dollar spent, there would be an economic return of between $3 and $34, depending upon the country.

The United Nations has set a goal of cutting in half by the year 2015 the number of people without access to safe drinking water and basic sanitation. Independent experts say that a concerted effort on the part of wealthier nations is necessary if that goal is to be reached.